I bought this book from Amazon in 2002 and used it during a ride from San Francisco to Los Angeles in August 2003.
It's a very good guide. The directions for their main route were quite detailed and usually clear. I got lost a couple of times, but never badly and it may not have been the book's fault. Milage totals were usually pretty close, although there were a couple of segments that were off somewhat. The guide is much more useful if you photocopy the pages with directions. Then you can use them as daily route slips. The book can be kept in a pannier during the trip to be brought out in the evening to get an overview of the next day's route and stuff you might see along the way.
I also enjoy the overall feeling that it was written by dyed-in-the-wool cyclists for dyed-in-the-wool cyclists. This authenticity comes out sometimes in little asides, such as the authors' comment that a northbound tunnel near Gaviota (CA) is like riding through a high-suction vacuum hose. If you've ridden a bicycle through that tunnel, you'd know how dead-on that description is.
I didn't give the book 5 stars (although I would have given it 4.5 if there was an option) because it doesn't provide much for the bicycle tourist who prefers hotels and hostels to camping. An appendix with a listing of youth hostels and a selection of cyclist-friendly hotels on the route would make the guide more complete. It would be especially helpful if the authors did this for the more remote regions on the route. The authors also might want to add a little more commentary and detail to the alternate routes they sometimes suggest. For example, the authors suggest an inland route along US101 as an alternate to Highway 1 through Big Sur when the road is closed (which happens fairly often) or during the height of the tourist season. Well, if you're going to suggest a 100-mile detour, do more than just put a shaded line on a not-very-detailed map. (By the way, I don't completely agree with the authors' assertion that Hwy 1 through Big Sur is too trafficy to comfortably ride during the tourist season. Maybe it is on weekends, but I went through on a Monday and traffic was only moderate and not particularly hard to deal with.)
Overall, though, this book is well worth the money.